When light is reflected from the surface of an object, the polarization property of the light changes. That is why the light reflected from the object has its polarization property determined by various pieces of information including the surface roughness, reflectance, and birefringence of the object and the orientation of the reflective surface. Thus, if light with a polarization property is separated, detected and converted into an electrical signal, those pieces of information can be obtained.
A shooting system of that type is generally used as means for imaging separately light that has been reflected from the surface of a tissue and light that has been reflected from inside of the tissue in a camera for medical and beauty treatment purposes such as an endoscope and a skin checker.
In order to detect light with a polarization property, according to a conventional method, a polarizer is arranged in front of the lens of a image capturing camera and a shooting session is carried out with the polarizer rotated according to the shooting condition. According to such a method, however, shooting sessions need to be performed a number of times with the polarizer rotated, thus taking a long time to get an image.
Thus, to overcome such a problem, some people proposed a method for getting an image using light with a different polarization property by arranging a polarizer having an axis of polarization in a predetermined direction in advance on the surface of an image sensor. For example, a Patent Document No. 1 discloses a device in which polarization filters are provided for some of the pixels of a solid-state image sensor. By making light with a polarization property incident on some pixels and by performing image processing on an image obtained from those pixels on which the light with a polarization property has been incident and an image obtained from other pixels, an image, from which the influence of reflection from the surface of the subject has been reduced, can be obtained.
Meanwhile, Patent Document No. 2 discloses an image capture device in which an optical system is formed by an array of two lenses and an image is shot through each of those lenses using light with a different polarization direction, thereby detecting the state of a dry or wet road surface.